Following a well-documented rise in the popularity of concrete shell application in the 20th century, thin concrete shells have experienced a global decline despite their potential as efficient structures with an economy of material use with aesthetics benefits. This phenomenon is subject to geographically determined socio-economic conditions and competition from other building solutions as a result of technological advancement in alternative construction systems. Importantly, their decline was attributed to limitations inherent to concrete shell formwork and construction methods. Being able to produce efficient shaping did not ensure that this method of construction is most cost efficient as it still remains difficult to construct double curved surfaces. The thesis addresses the limitations associated with past and present concrete shell building by proposing the use of actively-bent gridshells as re-configurable and reusable formwork for concrete shells to be designed and built. The hypothesis uses deployable scissor-jointed actively-bent gridshells as re-configurable and reusable formwork for concrete shell construction. This was developed from a series of Flash research (Benjamin, 2012) as student construction workshops to investigate the design and creation of actively-bent gridshells held between December 2008 and March 2011 in Sheffield. In this study, to understand this new system, scaled models of actively-bent gridshells were used as preliminary design aid. Deployed into three dimensional forms from a flexible flat grid mat, the structures were rigidized by bracing through triangulation restraints. The temporary rigid structure was subsequently enveloped with fabric onto which concrete was applied to create the concrete shell, thus acting as formwork. This formwork was then removed following the curing of the concrete cast to be reused repeatedly, or reconfigured into another concrete shell form. Hence, the thesis draws on the concepts, principles and ideas pertaining to three key architectural technologies: 1. concrete shell, 2. actively-bent gridshells and 3.fabric formwork. The thesis then presents a series of four prototype concrete shells constructed from different materials spanning between 1.3 meters and 2.45 meters in the workshops at the University of Edinburgh built between August 2014 and September 2015. For each experimental construction, the process of gridshell construction, fabric formwork preparation, concrete casting, gridshell formwork decentring and different design elements of openings, edges and anchorage abutments were analysed and discussed under the themes of construction, architectural tectonics and structure. The tectonic of process and material is understood and discussed based on the idea of stereogeneity (Manelius, 2012). Specifically, the relationship between gridshell as formwork and the concreting process was studied, analysed and assimilated in concrete shells built with progressive sophistication and elegance, culminating in a doubly-curved concrete shell that demonstrated both synclastic and anticlastic geometries, with further abutment simplification, edge leaning and physical openings incorporation. The study concludes with a physical concrete shell model formed by applying concrete onto fabric formwork to cover the Weald and Downland Jerwood gridshell. In the 1:20 scaled model, the proposed method is speculatively applied onto fabric stretched between pre-determined curvatures of the as-built gridshell. This formwork was subsequently removed for reuse, re-deployed and reconfigured. Using finite element analysis, the structural behaviour of the gridshell made of glass-fibre reinforced tubes and structural characteristics of the resultant concrete shell was checked. The interaction between the three technologies are discussed architectonically and structurally to inform guidelines for potential life-scale application. The thesis evidences the feasibility of the proposed system. It re-purposes a scaled model of a deployable gridshell as a physical modelling tool to facilitate concrete shell design, for both pure compression shells and "improper" shells, demonstrating its adaptability. It also promotes and reinvigorates concrete shells as possible architectural systems serving to instigate future research to revive concrete shell construction as an intelligent and intuitive way of creating structures with material economy, structural efficiency and visual elegance.

The use of recycled aggregates in concrete opens a whole new range of possibilities in the reuse of materials in the building industry. This could be an important breakthrough for our society in our endeavours towards sustainable development. The trend of the utilisation of recycled aggregates is the solution to the problem of an excess of waste material, not forgetting the parallel trend of improvement of final product quality. The utilisation of waste construction materials has to be related to the application of quality guarantee systems in order to achieve suitable product properties. Therefore the complete understanding of the characteristics of new material becomes so important in order to point out its real possibilities. The studies on the use of recycled aggregates have been going on for 50 years. In fact, none of the results showed that recycled aggregates are unsuitable for structural use. Only having inadequate number of studies in durability aspects, made recycled aggregates to be preferred just as stuffing material for road construction. My thesis, aimed to focus on the possibility of the structural use of recycled aggregate concrete based on a better understanding of its microstructure.To begin with the characteristics of the aggregates were established, to study their possible application in concrete production. After analysis, the dosage procedure was carried out in order to produce four concrete mixtures using different percentages of recycled coarse aggregates (0% (HC), 25% (HR25), 50% (HR50) and 100% (HR100)) with the same compression strength. Raw coarse aggregates (granite) and sand (crushed limestone) were used in the different concrete mixes.Macroscopic and microscopic examination were carried out in HC, HR25, HR50 and HR100 concretes in order to observe the durability effects. The macroscopic examination determined the aggregates distribution, composition, the contaminants and aureoles around adhered mortar. Microscopic examination was carried out by Optical light transmitted microscope Leica Leitz DM-RXP, using Fluorescence Thin Sections, in order to analyse the cement paste, the new and old interfacial transition zones, secondary reactions as well as damage. Original aggregates and cement paste, interfacial transition zones and alkali silica gel produced due to reactive aggregates present in adhered mortar were analysed by SEM and EDX-maps. Beside macro and micro observations, shear failure behaviour of recycled aggregate concretes was studied. Shear failure test was found more appropriate, as concrete properties had more influence in this type of failure behaviour compared to the flexural failure where the reinforcement plays the important role. Sixteen beam specimens were cast and the structural behaviour of these beams was analysed using four different transversal reinforcements for each kind of concrete. An analytical prediction of the experimental results are carried out using a numerical model (Modified Compression Field Theory), using the codes AASHTO LRFD, CSA, Eurocode-2 and expressions proposed in the Spanish code EHE-99.Organic and inorganic compounds were found to be released from waste materials through leaching and dispersed into the soil and surface water. The leaching of these compounds were measured employing different codes, the two Dutch codes (NEN 7341 and 7345) and the European Normative (EN 12457-2).Some recommendations are given as to the aggregates characteristics to be used in concrete mixes, taking into account the European standards for recycled aggregates. Also suggestions are made for the production process of concrete using recycled aggregate. Mechanical properties of recycled aggregate concrete are studied and they are compared with that of conventional concrete. Based on the durability of the concrete, some suggestions are proposed with respect to possible alkali silica reaction between new cement and original fine aggregates. It is also determined that the effect of the use of recycled aggregate on the beams' shear strength depend on the percentage of coarse aggregate substituted. The applicability of concrete recycled aggregate with respect to its environmental behaviour is demonstrated. In conclusion, some suggestions for future studies are made which would help us in the evolution of our understanding in this field.

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Considerando-se um cenário econômico bastante favorável em conjunto com avanços tecnológicos da ciência dos materiais e processos construtivos, nos últimos trinta anos, as cidades brasileiras têm apresentado um crescimento substancial, no que diz respeito à construção de edifícios residenciais e comerciais de múltiplos andares. Nos dias de hoje, estes edifícios apresentam níveis de esbeltez elevados e têm sido construídos com estruturas cada vez mais arrojadas englobando a experiência e o conhecimento dos engenheiros civis. Deste modo, o principal objetivo dos projetistas está associado à concepção de estruturas mais leves, nas quais o projeto estrutural requer um conhecimento teórico substancial, objetivando tornar compatíveis os requisitos arquitetônicos com as condições necessárias para a estabilidade. Assim sendo, o objetivo deste trabalho de pesquisa é o de investigar o comportamento estrutural estático e dinâmico de um edifício misto (aço-concreto) de 20 pavimentos quando submetido às ações dinâmicas do vento não determinísticas. Deste modo, no desenvolvimento do modelo computacional são empregadas técnicas usuais de discretização, via método dos elementos finitos, por meio do programa ANSYS. Para tal, o estudo apresenta os resultados de uma análise não linear geométrica para ações de serviço. A resposta dinâmica não determinística do modelo estrutural investigado, em termos dos valores máximos médios dos deslocamentos e das acelerações, foi obtida e comparada com os valores limites propostos por normas e recomendações de projeto. / Considering the favourable economic scenario and technological advances of material sciences and construction processes, in the last thirty years, the Brazilian cities have presented a substantial growth, with respect to construction of residential and commercial multi-storey buildings. Nowadays, these buildings present greater slenderness and have been constructed with more challenging structures that encompass the experience and knowledge of structural designers by using newly developed materials and technologies boosted by the ever-growing investigations on this field. As the structural designer main objective is related to produce increasingly lighter structures its conception requires a substantial amount of theoretical knowledge associated to structural design and construction processes, in order to make compatible the requirements of architecture with the necessary conditions for stability. This way, this research work aims to investigate the static and dynamic structural behaviour of a 20 story steel-concrete composite building, when submitted to the non-deterministic wind dynamic actions. The developed computational model adopted the usual mesh refinement techniques present in finite element method simulations implemented in the ANSYS program. The present study has considered the results of a geometric nonlinear analysis for serviceability limit states. The investigated structural model non-deterministic dynamic response, in terms of displacements and peak accelerations, was obtained and compared to the limiting values proposed by several authors and design standards.

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Considerando-se um cenário econômico bastante favorável em conjunto com avanços tecnológicos da ciência dos materiais e processos construtivos, nos últimos trinta anos, as cidades brasileiras têm apresentado um crescimento substancial, no que diz respeito à construção de edifícios residenciais e comerciais de múltiplos andares. Nos dias de hoje, estes edifícios apresentam níveis de esbeltez elevados e têm sido construídos com estruturas cada vez mais arrojadas englobando a experiência e o conhecimento dos engenheiros civis. Deste modo, o principal objetivo dos projetistas está associado à concepção de estruturas mais leves, nas quais o projeto estrutural requer um conhecimento teórico substancial, objetivando tornar compatíveis os requisitos arquitetônicos com as condições necessárias para a estabilidade. Assim sendo, o objetivo deste trabalho de pesquisa é o de investigar o comportamento estrutural estático e dinâmico de um edifício misto (aço-concreto) de 20 pavimentos quando submetido às ações dinâmicas do vento não determinísticas. Deste modo, no desenvolvimento do modelo computacional são empregadas técnicas usuais de discretização, via método dos elementos finitos, por meio do programa ANSYS. Para tal, o estudo apresenta os resultados de uma análise não linear geométrica para ações de serviço. A resposta dinâmica não determinística do modelo estrutural investigado, em termos dos valores máximos médios dos deslocamentos e das acelerações, foi obtida e comparada com os valores limites propostos por normas e recomendações de projeto. / Considering the favourable economic scenario and technological advances of material sciences and construction processes, in the last thirty years, the Brazilian cities have presented a substantial growth, with respect to construction of residential and commercial multi-storey buildings. Nowadays, these buildings present greater slenderness and have been constructed with more challenging structures that encompass the experience and knowledge of structural designers by using newly developed materials and technologies boosted by the ever-growing investigations on this field. As the structural designer main objective is related to produce increasingly lighter structures its conception requires a substantial amount of theoretical knowledge associated to structural design and construction processes, in order to make compatible the requirements of architecture with the necessary conditions for stability. This way, this research work aims to investigate the static and dynamic structural behaviour of a 20 story steel-concrete composite building, when submitted to the non-deterministic wind dynamic actions. The developed computational model adopted the usual mesh refinement techniques present in finite element method simulations implemented in the ANSYS program. The present study has considered the results of a geometric nonlinear analysis for serviceability limit states. The investigated structural model non-deterministic dynamic response, in terms of displacements and peak accelerations, was obtained and compared to the limiting values proposed by several authors and design standards.

Com base no crescimento exponencial das populações urbanas, a demanda por espaço para habitação tem crescido vertiginosamente. Para atender a estas necessidades, edificações cada vez mais altas e mais esbeltas são projetadas e vãos cada vez maiores são utilizados. Novos materiais são criados e aprimorados para que seja extraído o máximo de desempenho com o menor custo. Deste modo, esta dissertação tem como objetivo o estudo do comportamento e otimização do projeto estrutural de edifícios. Para tal, considera-se ao longo do estudo o projeto de uma edificação de concreto armado com 47 metros de altura e 15 pavimentos, submetida às ações das cargas usuais de projeto atuantes sobre edifícios residenciais, além das cargas de vento. No que tange ao desenvolvimento do modelo computacional são empregadas técnicas usuais de discretização, via método dos elementos finitos, por meio do programa ANSYS. Inicialmente, a resposta estática e dinâmica do modelo estrutural é obtida e comparada com base nos valores limites propostos por normas de projeto. A partir de análises qualitativas e quantitativas desenvolvidas sobre a resposta estrutural do modelo em estudo são utilizadas técnicas de otimização com o objetivo de modificar e aprimorar o desempenho estrutural do edifício analisado. / Based on the exponential growth of urban populations, the demand for space for housing has grown dramatically. To meet these needs, building ever higher and more slender are designed and increasing spans has been used. New materials are created and improved to be extracted maximum performance at the lowest cost. Thus, this research work aims to study the behaviour and optimization of buildings structural design. To do this, it is considered throughout the study the design of a reinforced concrete building with 47 meters high and 15 floors, subjected to the actions of usual design loadings on residential buildings in addition to wind loads. Regarding the development of the computational model, usual mesh refinement techniques are used, based on the finite element method simulations, and implemented in the ANSYS program. Initially, the structural model static and dynamic response is obtained and compared, based on the limiting values proposed by design standards. Based on the developed qualitative and quantitative analyses on the investigated structural model response, optimization techniques are used in order to modify and improve the structural performance of the analysed building.

Com base no crescimento exponencial das populações urbanas, a demanda por espaço para habitação tem crescido vertiginosamente. Para atender a estas necessidades, edificações cada vez mais altas e mais esbeltas são projetadas e vãos cada vez maiores são utilizados. Novos materiais são criados e aprimorados para que seja extraído o máximo de desempenho com o menor custo. Deste modo, esta dissertação tem como objetivo o estudo do comportamento e otimização do projeto estrutural de edifícios. Para tal, considera-se ao longo do estudo o projeto de uma edificação de concreto armado com 47 metros de altura e 15 pavimentos, submetida às ações das cargas usuais de projeto atuantes sobre edifícios residenciais, além das cargas de vento. No que tange ao desenvolvimento do modelo computacional são empregadas técnicas usuais de discretização, via método dos elementos finitos, por meio do programa ANSYS. Inicialmente, a resposta estática e dinâmica do modelo estrutural é obtida e comparada com base nos valores limites propostos por normas de projeto. A partir de análises qualitativas e quantitativas desenvolvidas sobre a resposta estrutural do modelo em estudo são utilizadas técnicas de otimização com o objetivo de modificar e aprimorar o desempenho estrutural do edifício analisado. / Based on the exponential growth of urban populations, the demand for space for housing has grown dramatically. To meet these needs, building ever higher and more slender are designed and increasing spans has been used. New materials are created and improved to be extracted maximum performance at the lowest cost. Thus, this research work aims to study the behaviour and optimization of buildings structural design. To do this, it is considered throughout the study the design of a reinforced concrete building with 47 meters high and 15 floors, subjected to the actions of usual design loadings on residential buildings in addition to wind loads. Regarding the development of the computational model, usual mesh refinement techniques are used, based on the finite element method simulations, and implemented in the ANSYS program. Initially, the structural model static and dynamic response is obtained and compared, based on the limiting values proposed by design standards. Based on the developed qualitative and quantitative analyses on the investigated structural model response, optimization techniques are used in order to modify and improve the structural performance of the analysed building.

Abstract High energy prices and new environmental policies have made geothermal energy increasingly popular. The EU, including Finland, aims to increase the use of renewable energy resources and reduce carbon emissions. Geothermal energy pile foundations, so-called energy piles, are considered a viable alternative technology for producing energy instead of traditional methods. Geothermal heat pump systems are economically efficient and renewable environmentally friendly energy production systems in which the ground acts as a heat source in winter and as a heat sink in summer. Energy piles are economical systems, as they act as dual-purpose structures in energy production and load transfer from buildings to the ground, avoiding extra expenses in ground boring solely for energy production. However, use of ground heat exchangers (GHE) for energy production in energy piles can result in temperature variations in the pile shaft and surrounding soil, in turn affecting the thermo-mechanical behaviour of pile shaft and soil in both structural and geotechnical terms. Despite large numbers of energy piles being installed, there is still a lack of reliable information and experience about the thermo-mechanical behaviour of these structures and their energy efficiency in cold climates. This thesis investigated the efficiency performance of energy pile foundations and their productivity in cold climates by considering different groundwater flow effects and short-term imbalanced seasonal thermal loadings. The structural and geotechnical bearing capacity of different types of energy piles fitted with GHEs were also evaluated, using numerical models, and the possibility of collapse due to use of thermal systems was examined. Use of the model to compare the performance of different GHEs in terms of their efficiency revealed that at a particular fluid flow rate, double U-tube systems had greater productivity than other systems tested. The results also indicated that using energy piles under medium groundwater flow can improve the productivity of systems by around 20% compared with saturated conditions with no groundwater flow. It was also concluded that in a design context, the structural bearing capacity of piles needs to be reduced due to the additional thermal stresses induced by heating/cooling pile operations. / Tiivistelmä Kasvaneet energiakustannukset ja kiristyneet ympäristösäädökset ovat lisänneet geotermisten energiaratkaisujen suosiota. EU, mukaan lukien Suomi, on asettanut tavoitteekseen lisätä uusiutuvien energialähteiden käyttöä ja vähentää hiilidioksidipäästöjä. Geotermistä energiaa hyödyntävä paaluperustukset, niin kutsutut energiapaalut, tarjoavat uudenlaisen teknologian vähäpäästöisen energian tuottamiseen. Geotermiset lämpöpumppujärjestelmät, maalämpöpumput, ovat taloudellisia ja ympäristöystävällisiä energiantuotantomenetelmiä, jotka talviaikaan siirtävät maaperään varastoitunutta energiaa rakennuksen lämmittämiseen ja vastaavasti jäähdyttävät rakennusta kesällä siirtämällä lämpöä maaperään. Energiapaalujen taloudellisuus syntyy siitä, että ne pystyvät palvelemaan rakennusta kahdessa roolissa. Ne ovat osa rakennuksen energiajärjestelmää ja toimivat samalla myös kantavana rakenteena, joka siirtää rakennuksen kuormia perustuksilta maaperään. Lämpöpumppujärjestelmän kytkeminen paaluihin voi johtaa lämpötilan vaihteluun paaluissa sekä niitä ympäröivässä maaperässä, mikä puolestaan vaikuttaa paalujen ja maaperän lämpömekaanisiin, rakenteellisiin sekä geoteknisiin ominaisuuksiin. Vaikka energiapaaluja on asennettu jo paljon, ei paalujen lämpömekaanisesta käyttäytymisestä tai energiatehokkuudesta kylmien ilmastojen alueilla ole vielä paljoa tutkittua tietoa. Tässä väitöstutkimuksessa selvitettiin numeerisesti energiapaalujen rakennuspaikan pohjaolosuhteista riippuvaa tuottopotentiaalia Skandinaavisissa olosuhteissa ja ilmastossa. Tarkastelut kohdistuivat erityisesti pohjavesivirtauksen sekä vuodenaikojen ja ilman lämpötilan vaihtelun vaikutuksiin. Tutkimuksessa arvioitiin myös paalujen lämpötilan vaihtelujen vaikutuksia paalujen geoteknisiin ja rakenteellisiin ominaisuuksia sekä kestävyyteen. Numeeristen simulaatiotulosten perusteella betonipaaluun asennetun U-putkirakenteen avulla saavutetaan paras tuottopotentiaali. Tulokset osoittivat, että kohtalainen pohjaveden virtaus parantaa systeemin tuottoa noin 20 % verrattuna tilanteeseen, jossa vedellä kyllästetyssä maassa ei tapahdu pohjaveden virtausta. Analyysitulokset osoittavat myös, että paalujen lämpötilavaihteluista aiheutuvat lisäjännitykset vähentävät paalujen kantokykyä, mikä tulee ottaa huomioon paalujen mitoituksessa.

Assessing existing bridges is an important task in the sustainable management ofinfrastructure. In practice, structural bridge assessments are usually conducted usingtraditional and standardised methods, despite knowledge that these methods oftenprovide conservative estimates. In addition, more advanced methods are available, suchas nonlinear finite element (FE) analysis, that are used for research purposes and cansimulate the structural behaviour of bridges more accurately. Therefore, it would beuseful to develop practical and reliable procedures for refined assessments using theseadvanced techniques.Focusing on the ultimate load-carrying capacity of existing concrete bridges, this thesispresents a procedure for structural assessments. The fundamental idea is to improve theassessment successively, as necessary to predict bridges’ structural behaviour adequately.The procedure involves a multi-level assessment strategy with four levels of structuralanalysis, and an integrated framework for safety verification. At the initial level (Level 1)of the multi-level strategy, traditional standardised methods are used, no failures arecovered implicitly in the structural analysis and action effects are verified using localresistances calculated using analytical models. In the subsequent enhanced levels (Levels2 – 4), nonlinear FE analysis is used for stepwise integration of the verification of flexural,shear-related and anchorage failures into the structural analysis. The framework for safetyverifications includes partial safety factor (PSF), global resistance safety factor (GRSF) andfull probabilistic methods. Within each of these groups, verifications of desired safetymargins can be conducted with varying degrees of complexity.To demonstrate and evaluate the proposed structural assessment procedure, comparativestudies have been carried out, based on full-scale tests of a prestressed concrete bridge.This was the Kiruna Bridge, located in the northernmost city in Sweden, which was duefor demolition as part of a city transformation project, necessitated by large grounddeformations caused by the large nearby mine. Thus, it was available for destructiveexperimental investigation within the doctoral project presented in this thesis. The bridgehad five continuous spans, was 121.5 m long and consisted of three parallel girders with a connecting slab at the top. Both the girders and slab were tested to failure to investigatetheir structural behaviour and load-carrying capacity. Non-destructive and destructivetests were also applied to determine the residual prestress forces in the bridge girders andinvestigate the in situ applicability of methods developed for this purpose. The so-calledsaw-cut method and decompression-load method were used after refinement to enabletheir application to structures of such complexity. The variation of the experimentallydetermined residual prestress forces was remarkably high, depending on the sectioninvestigated. There were also high degrees of uncertainty in estimated values, and thusare only regarded as indications of the residual prestress force.Level 1 analysis of the multi-level assessment strategy consistently underestimatedcapacity, relative to the test results, and did not provide accurate predictions of the shearrelatedfailure observed in the test. With linear FE analysis and local resistance modelsdefined by the European standard, Eurocode 2, the load-carrying capacity wasunderestimated by 32 % for the bridge girder and 55 % for the bridge deck slab. At theenhanced level of structural analysis (Level 3), nonlinear FE analyses predicted thecapacities with less than 2 % deviation from the test results and correctly predicted thefailure mode. However, for existing bridges there are many uncertainties, for instance,the FE simulations were sensitive to the level of residual prestressing, boundaryconditions and assumed material parameters. To accurately take these aspects intoaccount, bridge-specific information is crucial.The complete structural assessment procedure, combining the multi-level strategy andsafety verification framework, was evaluated in a case study. Experiences from theprevious comparative studies were used in an assessment of the Kiruna Bridge followingthe Swedish assessment code. The initial assessment at Level 1 of the multi-level strategyand safety verification, using the PSF method, indicated that the shear capacity of one ofthe girders was critical. The most adverse load case (a combination of permanent loads,prestressing and variable traffic loads) was further investigated through enhancedstructural analyses implicitly accounting for flexural and shear-related failures (Level 3).Nonlinear FE analysis and safety evaluation using the PSF method, several variants of theGRSF method and the full probabilistic analysis for resistance indicated that the permittedaxle load for the critical classification vehicle could be 5.6 – 6.5 times higher than thelimit obtained from the initial assessment at Level 1. However, the study also indicatedthat the model uncertainty was not fully considered in these values. The modeluncertainty was shown to have strong effects on the safety verification and (thus)permissible axle loads. The case study also highlighted the need for a strategy forsuccessively improving structural analysis to improve understanding of bridges’ structuralbehaviour. The refined analysis indicated a complex failure mode, with yielding of thestirrups in the bridge girders and transverse flexural reinforcement in the bridge deck slab,but with a final shear failure of the slab. It would be impossible to capture suchcomplexity in a traditional standardised assessment, which (as mentioned) indicated thatthe shear capacity of the girder limited permissible axle loads. However, nonlinear FEanalyses are computationally demanding, and numerous modelling choices are required.Besides a strategy for rationally improving the analysis and helping analysts to focus oncritical aspects, detailed guidelines for nonlinear FE analysis should be applied to reduce the analyst-dependent variability of results and (thus) the model uncertainty. Clearly, toensure the validity of bridge assessment methods under in situ conditions, theirevaluations should include in situ tests. This thesis presents outcomes of such tests, therebyhighlighting important aspects for future improvements in the assessment of existingbridges.